JPH0319836B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications The present invention relates to a single-shaft ship.

PRIOR ART In the case of a normal single-shaft ship with one propeller with the propeller axis in the stern centerplane (the vertical plane containing the centerline ship in horizontal section), the twisting of the flow through the sides and bottom of the ship causes In the stern flow field, there is a rotating flow in a plane perpendicular to the length direction of the ship. This rotating flow is generally called a stern bilge vortex, and a deceleration flow, that is, a wake, is concentrated at the center of this vortex due to separation of the boundary layer.

In a ship whose stern shape is symmetrical with respect to the hull center plane, the stern bilge vortex occurs symmetrically on both sides, and the rotation direction is inward, that is, clockwise rotation on the left side and counterclockwise rotation on the right side. By installing two propellers that rotate in the opposite direction to the vortex near the center of the stern bilge vortex, the independent efficiency of the propellers can be improved, and the energy loss due to separation of the boundary layer can be reduced in the form of wake gain. This can be expected to improve propulsion efficiency. However, in the case of a normal single-shaft ship, it is not possible to bring the centers of the stern bilge vortices that occur on both sides close to the propeller center, so it is difficult to obtain sufficient wake gain and make effective use of this. be. Furthermore, for example, in the case of a normal single-shaft ship with a right-handed propeller, the right side stern bilge vortex rotates to the left in the opposite direction to the propeller, so it can be used effectively, but the left side bilge vortex rotates counterclockwise in the opposite direction to the propeller. Since it is a clockwise rotation in the same direction as
This is not available. Additionally, on the right side of the propeller, the angle of attack of the propeller blade increases due to the stern bilge vortex rotating in the opposite direction, and on the left side of the propeller, the angle of attack is increased by the stern bilge vortex rotating in the same direction. Vibrations caused by the propeller occur due to the reduced angle. In the case of a normal single-shaft ship with a counterclockwise-rotating propeller, the left-right relationship is reversed, but a similar problem occurs.

In order to eliminate the above-mentioned drawbacks of ordinary single-shaft ships, various measures have been taken in the past, such as the following.

(a) The shape of the stern submerged area in front of the propeller is made asymmetrical to bring the stern vortices on both sides closer to the center of the propeller.

(b) The shape of the submerged part of the stern is made asymmetrical, so that a stern vortex is generated almost only on one side, and a propeller that rotates in the opposite direction is placed near the center of this vortex.

(c) Install current-variant fins in front of the propeller in the submerged stern section.

However, in (a) and (c) above, even if the center of the Ryogen's stern vortex could be brought closer to the propeller center to some extent, the Ryogen's vortex still exists, and the propulsion efficiency cannot be sufficiently improved. I can't wait. In addition, in (b) above, since the stern vortex is generated only on one side, the stern shape becomes complicated, the hull resistance increases, and problems arise with the arrangement of the propeller and main engine.

In addition, in the case of a normal single-shaft ship, the stern bilge vortex has the advantage of involving the bottom boundary layer and increasing the wake coefficient, but strong bilge vortices that cannot be concentrated within the propeller plane are generated on both sides of the stern. What to do is
This is disadvantageous because it increases the hull resistance.

For this reason, a so-called low-resistance hull type has been proposed in which the cross-sectional shape of the main hull from near the center of the hull to the stern is U-shaped, and the curvature of the surface of the main hull from near the center of the hull to the stern is almost the same on the side and the bottom. has been done.
If such a low-resistance hull form is adopted, hull resistance will be reduced because stern bilge vortices will hardly be generated, but propulsion efficiency will generally deteriorate because the wake coefficient cannot be expected to increase due to bilge vortices.

Purpose of the Invention The purpose of the present invention is to improve propulsion efficiency in a single-shaft ship employing a low-resistance hull type as described above by generating one vortex in the opposite direction within the plane of the propeller.

Composition of the Invention A single-shaft boat according to the present invention is equipped with one propeller having a propeller shaft in the center plane of the hull at the stern, and the cross-sectional shape of the main hull from the center of the hull to the stern is U-shaped, and from the center of the hull to the stern. In a single-shaft ship where the curvature of the main hull surface in the direction is almost the same on the ship side and the bottom, a bossing is installed at the stern of the main hull that is inclined with respect to the center plane of the hull in the opposite direction to the direction of propeller rotation when moving forward. A groove-like recess is formed between the bossing on the side where the propeller blade moves downward during forward movement and the main hull, and in the cross section of the square station 3/8,
The angle of inclination of the bossing centerline to the hull center plane is 20
~40°, and the lower end shape of the bossing in the cross section of each square station is approximately arc-shaped, and on the side where the propeller blades move upward during forward movement, the bossing in the cross section of each square station is close to the main hull. There is a relationship of 0.65≦ _l1 /D≦1.0 between the distance l ₁ from the point where it intersects with the center plane of the hull and the propeller diameter D, and on the side where the propeller blade moves downward during forward movement, the distance l 1 of each squarer station Between the distance l ₂ from the point where the bossing intersects with the main hull in the cross section to the hull center plane, the height h from the baseline of the main hull to this point, and the propeller diameter D -0.595l ₂ /D+0.9≦h There is a relationship of /D h/D≦-0.595l ₂ /D+1.2, and at the required location between square station 3/8 and 3/4 of the groove-like recess on the side where the propeller blade moves downward during forward movement. A suction port is provided, and a discharge port is provided at a required location between the square station 1/4 and 3/8 of the bossing on the side where the propeller blades move upward when moving forward, and water is sucked in from the suction port and discharged. It is characterized in that a pump that blows air from the air outlet is installed inside the hull.

Embodiments and Functions The drawings show the stern of a single-shaft ship according to the present invention, in which Fig. 1 is a side view, Fig. 2 is a cross-sectional view at 3/8 of the square station (hereinafter referred to as SQST),
FIG. 3 is a front view.

This ship is equipped with one propeller 2 having a propeller shaft 1 in the hull center plane C at the stern, and the main hull 3 has a symmetrical U-shaped cross-sectional shape from the vicinity of the hull center to the stern. The curvature of the surface of the main hull 3 from the vicinity of the center toward the stern is almost the same on the ship side. The direction of rotation of the propeller 2 during forward movement is clockwise rotation. The stern of the main hull 3 is provided with a bossing 4 that is inclined counterclockwise with respect to the hull center plane C in the opposite direction to the rotation direction of the propeller 2 during forward movement, and the bossing 4 and the main hull 3 cross each other. They are continuously connected by intermediate curved surfaces 5 and 6 in the form of circular arcs. A groove-like recess 7 is formed on the right side of the stern by the bossing 4, the intermediate curved surface 6, and the main hull 3. Further, the shape of the lower end portion 8 of the bossing 4 in the cross section of each sqst is approximately arcuate.

Slit-shaped suction ports 9 having relatively small widths in the longitudinal direction of the hull are provided near sqst 3/8, 1/2, 5/8, and 3/4 of the right intermediate curved surface 6, respectively. Also, the bossing 4 in front of the left side propeller 2
Slit-shaped outlets 10 having a relatively small width in the longitudinal direction of the hull are provided near sqst1/4 and 3/8, respectively. A pump 11 sucks water from these suction ports 9 and blows it out from a spout 10.
is provided inside the hull, and flow rate regulating valves 12 and 13 are provided in each pipe line between this pump 11 and each suction port 9 and each blowout port 10, respectively.

In Figure 3, B is the width of the ship, r is the radius of the right side intermediate curve 6 in the cross section of each sqst, and sqst
From 3/8 to 1·1/4, the ratio n/B of the radius r to the ship width is approximately 0.36 to 0.96.

P ₂ is the right side intermediate curved surface 6 in the cross section of each sqst
and the contact point of the main hull 3, T is the height from the baseline bl of the main hull 3 to this contact point _P2 (contact point height),
M ₂ is a contact line connecting contact points P ₂ in each sqst. Then, at sqst3/8~1・1/4, the ratio T/B of this contact point height T and ship width B is about 0.28~
0.103, and the angle α of this contact line M ₂ with respect to the baseline bl is approximately 32.5°. In addition, P ₁ is each sqst
is the contact point between the left side intermediate curved surface and the main hull 3 in the cross section, and M ₁ is the contact line connecting these contact points P ₁ .

L ₁ is the intersection point where bossing 4 intersects main hull 3 in the cross section of each sqst on the left side, l ₁
is the distance (intersection distance) from this intersection Q ₁ to the hull center plane C, and N ₁ is the intersection line connecting the intersection Q ₁ in each sqst. Also, D is the propeller diameter, and the intersection distance l ₁
and propeller diameter D, there is a relationship of 0.65≦l ₁ /D≦1.0.

Q ₂ is the intersection point where the bossing 4 intersects the main hull 3 in the cross section of each sqst on the right side, l ₂ is the distance from this intersection Q ₂ to the hull center plane C (intersection distance),
h is the height from the baseline bl to this intersection Q ₂ (intersection height), and N ₂ is an intersection line connecting the intersection Q ₂ in each sqst. Then, the intersection distance l ₂ and the intersection height h
and the propeller diameter D, there is a relationship of -0.595l ₂ /D+0.9≦h/D h/D≦-0.595l ₂ /D+1.2.

cl is the bossing centerline in the cross section of sqst3/8, and β is the inclination angle of the bossing centerline cl with respect to the hull center plane C. Although this inclination angle β is 32° in this embodiment, it may be in the range of 20 to 40°. The bossing centerline in the cross section of sqst2.1/2 is within the hull center plane C, and the cross-sectional shape ahead of this is symmetrical with respect to the hull center plane C. S
is a curve connecting the intersection of the bossing center line and the lower part of bossing 4 in the cross section of each sqst between sqst2・1/2 and 3/8, and this curve S is on the left and right sides of the bossing center line cl at sqst3/8. Connect asymmetrically.

Since the stern of the single-shaft ship mentioned above has a so-called low-resistance hull shape, almost no stern bilge vortex is generated, and the hull resistance is small. In addition, on the right side of the propeller shaft 1, the upward counterclockwise flow flowing in from the bottom and side of the ship is caused by the groove-like recess 7.
It is further guided upward and counterclockwise, resulting in a large upward and counterclockwise flow. On the left side of the propeller shaft 1, the upward clockwise flow that has flowed in from the bottom and side of the ship is reversely guided downward and counterclockwise by the bossing 4, and becomes a small upward clockwise flow. Since the upward and counterclockwise flow on the right side is larger than the upward and clockwise flow on the left side, the flow on both sides becomes a counterclockwise flow centered on the propeller shaft 1 as a whole. The flow flows into the propeller blades as a rotating flow, that is, a vortex, in the direction opposite to the direction of rotation within the plane of the propeller. Therefore, although the hull resistance is reduced because almost no bilge vortices are generated, one vortex in the opposite direction is generated in the plane of the propeller, which improves the propulsion efficiency and reduces the hull resistance caused by the propeller. vibration is significantly reduced, and cavitation and resulting corrosion are prevented.

FIG. 4 shows the results of an electronic computer analysis of the state of water flow in the stern of the single-shaft vessel mentioned above. From the results in the same figure, it is clear that a large upward counterclockwise flow occurs on the right side of the propeller shaft, and a small upward clockwise flow occurs on the left side. It can be seen that a vortex is generated.

This fact has also been confirmed through water tank experiments using models.

In addition, in the above-mentioned ship, the pump 11 sucks the boundary layer from the suction port 9 on the right side, preventing separation that occurs in the groove-shaped recess 7, and the water sucked in from the suction port 9 on the left side. Gen side air outlet 1
It is blown out from 0. The wake is concentrated within the circle of the propeller surface by the suction and blowout of the two shafts, and the rotational flow of the vortex is arranged in a circular shape in the opposite direction of the propeller. You can expect a reduction in vibration.

The inclination angle β of the bossing center line cl in the previous period with respect to the hull center plane C, the relationship between the intersection distance l ₁ on the left side and the propeller diameter D, the relationship between the intersection distance l ₂ on the right side, the intersection height h, and the propeller diameter D The relationship between these factors affects the strength and position of the vortices generated within the plane of the propeller, and if these deviate from the previous range, sufficient effects will not be obtained. Also, these relationships are
It is adjusted appropriately within the above range depending on the shape of the ship so that an optimal vortex is generated within the plane of the propeller.

This invention can of course be applied to a single-shaft ship equipped with a counterclockwise rotating propeller. In this case, the shape of the stern section will be opposite to that of the above embodiment.

Effects of the Invention The stern hull shape of the single-shaft boat according to the present invention is equipped with one propeller having a propeller shaft within the center plane of the stern hull, and the cross-sectional shape of the main hull from near the center of the hull to the stern is U-shaped. Since the curvature of the main hull surface from near the center toward the stern is almost the same on the ship side and the bottom, so-called stern bilge vortices hardly occur, and the hull resistance is small. At the stern of the main hull, a bossing is provided that is inclined in the direction opposite to the direction of propeller rotation when moving forward with respect to the center plane of the hull, and between the bossing on the side where the propeller blades move downward when moving forward and the main hull. A groove-like recess is formed,
Since there is the above-mentioned relationship between the bossing and the main hull, it is possible to generate a single vortex in the opposite direction within the plane of the propeller. Therefore, the hull resistance can be reduced and at the same time the propulsion efficiency can be improved, and the overall required horsepower can be reduced. In addition, since the vortex concentrates within the plane of the propeller,
Vibration of the hull due to the propeller is significantly reduced, and cavitation and the corrosion caused by it are prevented. Furthermore, since the main hull has a simple shape with only a bossing provided, the stern section is easy to construct. Furthermore, suction ports are provided at required locations in the groove-shaped recesses, and outlet ports are provided at required locations on the bossing on the opposite side, and a pump is installed inside the hull that sucks water from the suction port and blows it out from the outlet. This prevents separation that occurs in the groove-like recesses, concentrates the wake within the circle on the propeller surface, and arranges the rotational flow of the vortex into a circular shape facing the opposite direction to the propeller, further increasing propulsion efficiency. At the same time, the vibration of the hull due to the propeller is further reduced.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a side view of the stern of a single-shaft ship, FIG. 2 is a cross-sectional view along the line of FIG. The figure is a drawing equivalent to Figure 3, showing the results of computer analysis of the state of water flow in the stern section. DESCRIPTION OF SYMBOLS 1... Propeller shaft, 2... Propeller, 3... Main hull, 4... Bossing, 8... Lower end of bossing, 9... Suction port, 10... Air outlet, 11...
…pump.

Claims (1)

[Claims] 1. 1. Having a propeller shaft in the center plane of the hull at the stern.
In a uniaxial ship, the main hull has two propellers, the main hull has a U-shaped cross-sectional shape from the center of the hull to the stern, and the curvature of the main hull surface from the center of the hull to the stern is almost the same on the side and the bottom. A bossing is provided at the stern of the main hull that is inclined in the opposite direction to the direction of propeller rotation when moving forward with respect to the center plane of the hull, and a groove is formed between the bossing on the side where the propeller blades move downward when moving forward and the main hull. A shaped recess is formed, and in the cross section of the square station 3/8,
The angle of inclination of the bossing centerline to the hull center plane is 20
~40°, and the lower end shape of the bossing in the cross section of each square station is approximately arc-shaped, and on the side where the propeller blades move upward during forward movement, the bossing in the cross section of each square station is close to the main hull. There is a relationship of 0.65≦ _l1 /D≦1.0 between the distance l ₁ from the point where it intersects with the center plane of the hull and the propeller diameter D, and on the side where the propeller blade moves downward during forward movement, the distance l 1 of each squarer station Between the distance l ₂ from the point where the bossing intersects with the main hull in the cross section to the center plane of the hull, the height h from the baseline of the main hull to this point, and the propeller diameter D -0.595l ₂ /D + 0.9 ≦ There is a relationship of h/D h/D≦-0.595l ₂ /D+1.2, and the required location between square station 3/8 and 3/4 of the groove-like recess on the side where the propeller blade moves downward during forward movement. A suction port is provided at the front, and an outlet port is provided at a required location between the square station 1/4 and 3/8 of the bossing on the side where the propeller blades move upward when moving forward, and water is sucked in from the suction port. A single-shaft ship is characterized in that a pump is installed inside the hull to blow out this water from an outlet.